[Interactions between the nervous and the immune system]

The immune and nervous systems have the capacity to modulate inflammatory processes in an additive, synergistic or antagonistic way. In addition to direct effects, feed-back systems connecting immune and nervous systems exist which provide the basis for a better understanding of the modulation of inflammatory reactions by the central nervous system (nervous as well as neuropsychological influences). It is well established that immunocompetent cells, but also endothelial, epithelial and mesenchymal cells induce and regulate inflammation by production of cytokines. However, the expression, synthesis and secretion of neuropeptides by cells of the immune system or even connective tissue cells has only been recognized recently. These findings indicate that non-neuronal cells in the periphery can feedback to the nervous system by secretion of neuropeptides (e.g. modulation of an afferent signal by interaction of peripherally produced neuropeptides with nerve endings). Nitrogen monoxide has recently been shown to act as an important mediator of inflammatory phenomena and to play an important role in neurotransmission. The rapidly accumulating knowledge of the nature metabolism of this highly reactive substance indicate new therapeutic options in the area of neuroimmunology.